1. Field of the Invention
The present invention relates to a knee protection airbag device which protects the knees of a seated vehicle occupant with an airbag expanding and inflating by admitting inflation gas.
2. Description of Related Art
In the prior art, Japanese Patent Laid-Open No. Hei 9-123863 shows a device for protecting the knees of a vehicle occupant. This prior art illustrates a device located below the column cover to protect the knees of a driver with an expanding and inflating airbag. This device includes a case opened rearward for housing the folded airbag, and an airbag cover covering the case opening and including a door portion openable upon airbag deployment. The airbag cover is assembled with the case. Around the airbag cover, there is separately arranged an interior decoration member of a vehicle. The door portion includes an upper door openable upward and a lower door openable downward.
In an airbag device of this kind, when the airbag protrudes rearward of the vehicle by admitting inflation gas from the inflator, a great reaction force forward of the vehicle is applied to the case. Because of this reaction force, the case is likely to move forward of the vehicle together with the airbag cover, thereby causing a gap between the airbag cover and the interior decoration member. The airbag expanding and inflating may go into this gap.
It is conceivable to stiffen the case itself to suppress the movement of the case. However, it causes the weight increase of the case, and further of the entire airbag device, which goes against the recent needs for the weight reduction of a vehicle.